(CNSNews.com) – As the first of a series of crucial meetings on nuclear issues began Monday, Iran’s government reiterated its defiance of the international community, saying that as far as it was concerned, the question was settled.

“We will never negotiate Iran’s undeniable rights,” President Mahmoud Ahmadinejad told reporters in his first press conference since his contested re-election sparked the country’s most serious unrest in three decades.

“From our point of view, Iran’s nuclear issue is over,” he said.

The Iranian government argues that it is as entitled as any other country to develop a nuclear energy program. The U.S. and others suspect the program is a cover for an attempt to build nuclear weapons capability, and the U.N. Security Council has imposed three sets of sanctions over Iran’s refusal to suspend uranium enrichment.

Ahmadinejad’s statement came on the day the U.N.’s nuclear watchdog, the International Atomic Energy Agency (IAEA), began a board of governors’ meeting in Vienna.

The meeting leads into the once-a-year IAEA general convention next week, bringing together all 150 member states for five days of deliberations where Iran and North Korea are both expected to feature prominently.

Later in the month, meetings at the United Nations in New York and a gathering of the G20 industrialized and developing nations in Pittsburgh will again discuss the two countries’ nuclear programs.

The Obama administration earlier gave Tehran until late September to accept an international offer of direct talks in return for a freeze on uranium enrichment, failing which Washington has signaled tougher sanctions. Iran rejected two earlier offers, in 2005 and 2008.

Ahmadinejad said Monday he did not recognize deadlines. He was, however, willing to “discuss world issues” with President Obama, he said.

As he has every year since taking office in 2005, Ahmadinejad plans to attend and address the U.N. General Assembly opening session later this month. Obama also will be at the U.N., both for the General Assembly debate and a special Security Council meeting on nuclear proliferation and disarmament.

In Vienna on Monday, IAEA head Mohamed ElBaradei told the agency’s 35-member board of governors that Iran should clear up lingering questions about its nuclear activities.

“Iran needs to respond fully to all the questions raised by the agency in order to exclude the possibility of there being military dimensions to its nuclear program,” he said.

Israel and France have both publicly raised allegations that ElBaradei, who ends 12 years at the helm of the IAEA in December, has not made public everything the agency knows about Iran’s activities. He is expected to come under pressure in the coming days to release purported annexes to released reports which he is suspected of holding back on the subject.

On Monday, ElBaradei criticized the suggestions that the IAEA was holding back vital information, calling reports to that effect “politically motivated and totally baseless.” Attempts to influence the secretariat’s work “and undermine its independence and objectivity” violated the IAEA statute and should stop, he said.

The tougher sanctions being mulled against Tehran if it does not cooperate could include a blockade on gasoline imports which account for about 40 percent of Iran’s needs.

In an apparent bid to preempt such an eventuality, Ahmadinejad won a pledge at the weekend from Venezuelan President Hugo Chavez, a close ally who shares Tehran’s hostility towards the U.S., to provide 20,000 barrels of gas a day if sanctions are imposed.

Speaking at a joint press conference with Ahmadinejad, Chavez – on his seventh official visit to Iran – called the agreement to supply gas in exchange for Iranian machinery “a strategic move.”